The outstanding English composer and poet, Arnold (Edward Trevor) Bax, was born into a Victorian upper-middle-class family, of Dutch descent. He grew up in Ivy Back, a mansion on top of Haverstock Hill, Hampstead. Because of the family affluence, Bax never had to take a paid position, and was free to pursue most of his interests; a sharp contrast to the life of too many Britons, who suffered abject poverty in the infamous slums. Bax displayed early that he was fitted with a powerful intellect and a great musical talent, especially at the keyboard. Playing the Wagner operas at the piano were amongst Bax's favorite activities – one of Bax's first intimate meetings with art music was Tristan und Isolde and its influence is seen in many of Bax's later works ( e.g. Tintagel). Bax was taught at home, but received his first formal musical education at age 16 from Cecil Sharp and others at the Hampstead Conservatory. Bax was accepted to the Royal Academy of Music in 1900 where he remained until 1905. At the Academy, Bax was taught composition by Frederick Corder, the Piano by Tobias Matthay , and the Clarinet by Egerton. In his composition classes, Corder emphasized the examples of Franz Liszt and Richard Wagner, and pointed to their liberal approach to classical form, which led Bax to develop a similar attitude. Bax also had an exceptional ability to sight-read and play complex orchestral scores at the piano, which won him several medals at the Academy. He also won prizes for best musical composition, including the Battison-Haynes prize and the competitive Charles Lucas medal.

Arnold Bax had a sensitive and searching soul and drew inspiration from a wide range of sources. He was a voracious reader of literature, and in this way he happened upon William Butler Yeats's The Wanderings of Oisin and Other Poems in 1902 . Bax proved highly receptive to the soft, melancholy moods of the Irish Literary Revival, and found in Yeats a powerful muse, from which he derived a life-time of inspiration. He developed an infatuation with Ireland, and began travelling extensively there. Bax visited the most isolated and secluded places, eventually discovering the little Donegal village Glencolumbkille, to which he returned annually for almost 30 years. Here, Bax drew inspiration from the landscape and the sea, and from the culture and life of the local Irish peasants – many of whom Bax regarded as close friends. Bax's encounter with the poetry of Yeats and the landscapes of Ireland, resulted in many new works both musical and literary. The String Quartet in E (1903), which later was worked into the orchestral tone-poem Cathaleen-Ni-Houlihan (1905) are fine examples of how Bax began to reflect Ireland in his music. Not only did Bax emerge as a surprisingly mature composer with these works, he also developed in them floating and undulating 'impressionistic' musical textures, using orchestral techniques not yet heard – not even from Claude Debussy . Many of the works Bax wrote in the period from 1903 to 1916 can be seen as musical counterparts to the Irish Literary Revival. The tone-poems Into The Twilight (1908), In The Faery Hills (1909), and Rosc-catha [Battle hymn] (1910) echo the themes of the Revival and especially the soft, dreamy mood of many poems and stories.

The Irish influence is only one of many found in Bax's music. An early affinity with Norway and the literature of Bjørnstjerne Bjørnson brought themes and moods from the Nordic countries into his music. From 1905 to 1911 Bax constantly alternated between using Nordic and Celtic themes in his compositions. Bax even attempted to teach himself some Norwegian, and in the song The Flute (1907) for voice and piano, Bax set an original poem by Bjørnson successfully to music. Later and fine examples of Bax's Nordic affinity are Hardanger for two pianos (1927) and the orchestral tone-poem The Tale the Pine-Trees Knew (1931).

In 1910, a youthful fling with a Ukrainian girl, Natalia Skarginska, brought Arnold Bax to St Petersburg, Moscow and Lubny near Kiev , which led to a fascination for Russian and Slavonic themes. The relationship with Skarginska resulted in an emotional agony from which Bax never completely recovered. His conflicted feelings are perhaps reflected in the First Piano Sonata in F sharp (1910, revised 1917-1920). The influence from Russia and the Ukraine can also be seen in two works for solo piano from 1912; Nocturne–May Night in the Ukraine, and Gopak (Russian dance). In 1915 appeared In a Vodka Shop also for solo piano. In 1919 Bax was one of four British composers to be commissioned to write orchestral music, which was to serve as interludes at Sergei Diaghilev's Ballets Russes in London this season. For the commission Bax incorporated the three above-mentioned piano works of Russian themes into Russian Suite for orchestra. In 1920 Bax wrote his final score of a clearly Russian theme. It was incidental music to J. M. Barrie's whimsical play The Truth About the Russian Dancers. The Russian influence is found in many of Bax's further scores, and especially predominant in Symphonies No. 1 to 3.

Not long after Bax returned to Britain, Arnold Bax married Elsita Sobrino - a childhood friend - in January 1911. They settled in Bushy Park Road, Rathgar, Dublin. Here, Bax's brother Clifford introduced them to the intellectual circle which met at the house of the poet, painter and mystic George William Russell. Bax had already had some of his poems and short stories published in Dublin, and to the circle he was simply known by his pseudonym Dermot O'Byrne (the name was possibly inspired by a renowned family of traditional musicians in Donegal). As Dermot O'Byrne, Bax was specifically noted for Seafoam and Firelight, published in London by the Orpheus Press in 1909 and numerous short stories and poems published in different media in Dublin. It was at Russell's house where Bax one night met Irish Republican Patrick Pearse. According to Bax they got on very well, and although they met only once the execution of Pearse following the Easter Rebellion in 1916, prompted Bax to compose several laments. The most noted of these are In Memorian Patric Pearse (1916), which Bax dedicated 'I gcuimhne ar bPadraig mac Piarais'.

The threat of war lead to the dissolution of the Rathgar Circle, as many members fled Ireland and Europe. Arnold Bax and his family returned to London - it was the loss of a blissful life. Bax avoided conscription because of a heart-condition, and spent the war years composing profusely. Although World War I unleashed previously unimagined horrors upon the world, it was the Easter Rebellion and the destruction of Dublin that greatly disturbed Bax. As Bax's Ireland – a haven and a retreat – was lost to bitter conflict and war, he sought refuge in a liaison with the younger pianist Harriet Cohen. What had started out as a purely professional relationship - Harriet Cohen playing and championing Bax's piano music - developed into a passionate relationship. Yet, their love could not be sanctioned by the contemporary social code, which brought Bax and Cohen considerable emotional suffering. Ironically, but perhaps not unexpectedly, this difficult period in Bax's life led to the composition of several attractive tone-poems, including Summer Music (1916), Tintagel (1917) and November Woods (1914-1917). In Tintagel, Bax reached back to legends and dreams and specifically that of the doomed lovers Tristan and Isolde. Tintagel is undoubtedly the most well-known of Bax's tone-poems, and especially for its colorful evocation of the sea. Bax's relationship with Cohen led some commentators to assume a Freudian link between Bax's alleged sexual passion and the sea-theme in Tintagel. However, the opening of Harriet Cohen's private papers and the research into them by scholars – such as the Norwegian musicologist Thomas Elnaes – indicates that such a link is at itbest speculative. Bax's works from this time reflect deep psychological conflicts that point forward to the passionate yet deeply troubled First Symphony in E flat, completed in 1922. After the war British music was in demand as never before in England, and Bax won considerable fame with his works, which were widely performed.

From 1928 onwards Arnold Bax ceased to travel to Glencolumbkille and instead began his annual migration to Morar , west Scottish Highlands, to work. Bax would sketch his compositions in London, and take them to the Station Hotel at Morar for the winter to orchestrate them. At this time, Bax found a new love in Mary Gleaves, and she accompanied him to Scotland. In the Morar period, which lasts until the outbreak of World War II, Bax rediscovered his interest for Norway and the Nordic countries, and found a new muse in the Finnish composer Jean Sibelius. Bax orchestrated Symphonies Nos. 3 to 7 at Morar but also several of his finest orchestral works including the three Northern Ballads. Bax's seven symphonies were composed within a relatively short span of time, and are perhaps the most coherent cycle of symphonies by any composer. The symphonies are distinguished by their three-movement structure, as opposed to the 'usual' classical four. They reflect Bax's many influences, and are profound works of art, with a deep psychological dimension tied up to evocations of scenery. The symphonies earned Bax a reputation as the successor of Sir Edward Elgar, as Ralph Vaughan Williams, for instance, only had completed four symphonies by the time Bax completed his seventh.

Arnold Bax received a knighthood in 1937 (knight bachelor), but Bax was not entirely prepared to enjoy this honour. He contended that there was a conflict between the knighthood and his profound affinity with Ireland, but accepted nonetheless. Also, a feeling that his creative energies were drained, became manifest; Bax explained to his friends that he felt tired, restless and lonely. He contended that he had a hard time 'growing up' - increasing age depressed him and he gradually succumbed to alcoholism. Bax also felt alienated by the new developments in Modernistic composition, and realized and lamented that his style was falling out of fashion.

In 1942 Arnold Bax was appointed Master of the King's Music , a decision the British musical establishment was not altogether happy with. By many, Bax was considered an untypical English composer, some especially pointing to the 'Irishness' of his music. Of Bax's later works, only the film scores for Malta and Oliver Twist were really successful. Although they earned Bax a renewed public acclaim, the works could not compensate for him being regarded as somewhat of a musical fossil by contemporary composers and critics. Bax retreated from the public scene and lived quietly at The White Horse Hotel in Storrington, Sussex.

In 1929 the Father Mathew Feis - a competitive music festival organized by the Capuchin Fathers - invited Arnold Bax to become adjudicator to the festival. It was Irish pianist Tilly Fleischmann who suggested him, knowing that Bax was familiar with Ireland and Irish conditions. This was also the first time Bax met Irish musicians in Ireland - other than folk musicians. In Cork, Bax was introduced to outstanding musicians such as the pianist Charles Lynch and the singer Maura O'Connor, both to give many performances of Bax's music. Bax's first visit to Cork was the beginning of a 25 year long friendship between Bax and the Fleischmann family. As performances of Bax's music grew increasingly rare in Britain, Tilly Fleischmann demonstrated to Bax that his music had wide appeal in Ireland. Bax, however, did little to act on this and to support further efforts, and Bax's music was not heard nationwide in Ireland until Aloys Fleischmann Jr. began conducting Bax's orchestral works with the Irish Radio Orchestra in Dublin, just after the end of the war. In 1946 Bax became external examiner with both University College Cork and University College Dublin, and he also gave individual tuition to young aspiring Irish composers. Bax received an honorary doctorate degree from the National University of Ireland in 1947.

In 1953 Arnold Bax was further honoured by appointment as a Knight Commander of the Royal Victorian Order (KCVO), an honour within the Queen's personal gift. Bax passed away during a visit to the Fleischmann's later that year - possibly from a complication of his heart-condition. One of his last compositions was Coronation March for Queen Elizabeth II. Bax is buried at St. Finbarr's Cemetery in Cork City.

The musical style of Arnold Bax blended elements of Romanticism and Impressionism, always with a strong Celtic influence. His orchestral scores are noted for their complexity and colorful instrumentation. Bax's poetry and stories, which he wrote under the pseudonym of Dermot O'Byrne, reflect his profound affinity with Irish poet William Butler Yeats , and are largely written in the tradition of the Irish Literary Revival. Not long before he died, Bax was asked by the editor of the The World of Music which were his own preferred works. Bax provided the following selection: The Garden of Fand (1916); Symphony No. 3 (1929); Winter Legends (1930); The Tale the Pine Trees Knew (1931); Symphony No. 6 (1936).